p27^Kip1 is Detected on Most Gastric MALT Lymphomas, but not Large Cell Lymphomas

抄録

We investigated the relationship of gastric mucosa-associated lymphoid tissue (MALT) lymphoma tumorigenesis to Helicobacter pylori infection, the t (11 ; 18) translocation, and alterations in cell cycle regulators. We sought to assess the implications of altered expression of p27^Kip1, a cyclin-dependent kinase inhibitor, on high-grade transformation and responsiveness to eradication therapy. We used immunohistochemistry to examine p27^Kip1, p53, and Ki-67 expression in 23 MALT lymphomas, five diffuse large B-cell lymphomas (DLBCLs), and four DLBCLs associated with MALT lymphoma. All of the MALT lymphomas were positive for p27^Kip1 expression and negative for p53 with a low Ki-67 index, regardless of the sensitivity of these cells to eradication. All DLBCLs were negative for p27^Kip1 and positive for p53, exhibiting a high Ki-67 index. In DLBCLs with MALT lymphoma, p27^Kip1 expression was absent from both the MALT and large cells components. In all of these lymphomas, the MALT components were negative for p53 and displayed a low Ki-67 index, while the large cell components were positive for p53 with a high Ki-67 index. The expression patterns of the DLBCLs differed significantly from those of the MALT lymphomas. p27^Kip1 was not detected in either component of DLBCL with MALT lymphoma, suggesting that decreased expression of p27^Kip1 in the MALT component may be related to high-grade transformation. Thus, p27^Kip1 expression in morphological MALT lymphomas could be useful tool to predict high-grade transformation to DLBCL.